Preparation of alkylaromatic hydrocarbons suitable as detergent alkylate



United States Patent Q 3,351,672 PREPARATIDN (PF ALKYLAROMATIQ HY- DROCAREEONS SUITABLE AS DETERGENT ALKYLATE Robert T. Adams, Lafayette, and Mack 15. Hughes, Al-

harry, @aiiti, assignors to Chevron Research Company, a corporation of Delaware No Drawing. Fiied Mar. 10, 1965, Ser. No. 438,719 6 Claims. (Cl. 260-671) The present invention relates to the preparation of alkylaromatic hydrocarbons suitable for sulfonation and neutralization to produce detergent alkylate. More particularly, the invention has to do with the preparation of detergent alkylate involving the alkylation of a suitable aromatic compound, for example, benzene with fractions of l-olefins having 10 to 20 carbon atoms to produce detergent alkylate fractions which when combined and sulfonated yield a sulfonate product characterized by a low content of unsulfonated oil comprising unsulfonated hydrocarbons.

It is known to produce detergent alkylate convertible by sulfonation and neutralization to a highly detergent active material by alkylating benzene or other suitable aryl compound, such as the monophenyl compounds toluene or xylene, with olefinic alkylating reaction, such as l-olefins of appropriate carbon content, in the presence of a FriedelCrafts catalyst, such as hydrofluoric acid.

The resulting alkylation reaction mixture is treated, usually by distillation, to obtain a heart-cut fraction, i.e., one substantially free of materials having a lower or higher boiling point than that of the desired alkylate in which the alkyl radicals correspond in carbon content to that of the alkylating olefinic reactant used in the alkylation step.

Heart-cut alkylate as thus obtained is then neutralized with an appropriate base, such as with sodium hydroxide to obtain sodium alkyl aryl sulfonate.

The sulfonation step involved in the process of converting alkylaromatic hydrocarbons to detergent active material gives rise to a number of problems which if not overcome impart certain undesirable characterstics to the final product, thus rendering it commercially unacceptable.

One problem of the sulfonation reaction is the presence in the final product of a high residue of unsulfonated hydrocarbons, commonly called unsulfonated oil. This presence of unsulfonated oil is responsible for undesirable effects, including tackiness and poor foaming performance. For these reasons a low unsulfonated oil content is specified,an amount not exceeding about 1% by weight based on detergent active material being generally required by commercial manufacturers.

Terminal olefins, i.e., l-olefins having 10 to 20 carbon atoms, obtained by cracking petroleum or parafiin waxes, are particularly desirable alkylating agents. Cracked paraffin wax olefins, because of their essentially straight chain structure, are highly suitable in the preparation of biologically soft detergent i.e., materials that are readily degraded by bacterial action. In contrast, the branchedchain alkylaromatic detergents, for example, those derived from C C polypropylene benzene, are biologically hard, i.e., resistant to biodegradation. However, while detergent alkylates produced from C -C cracked paraffin wax olefins are desirable because of their biodegradation properties, detergent products derived therefrom have an intolerably high content of unsulfonated oil.

It is therefore an object of the present invention to prepare from C -C l-olefins a detergent alkylate convertible to the final product characterized by a low content of unsulfonated oil.

In accordance with the invention two contiguous frac- ICC tions obtained from a whole mixture of C -C cracked parafiin wax olefins, a low-boiling fraction and a highboiling fraction, are first separately subjected to alkylation conditions in the presence of benzene and appropriate catalyst, e.g., hydrofluoric acid or aluminum chloride to product two alkylation products, or alkylates. Each is then separately distilled to obtain heart-cut alkylate, i.e., alkylate of desired purity and boiling range. The alkylates are then combined into one alkylate product, which can be converted by sulfonation and neutralization to a final detergent active material having a low unsulfonated oil content.

In carrying out the invention, it is important that the low and high-boiling fractions differ widely throughout their boiling point ranges. The low-boiling fraction has a boiling point range in F., from about 3.0 to 5.8 times that of the high-boiling fraction, obtained by dividing the boiling range of the low-boiling fraction by that of the high-boiling fraction. For example, if the lowboiling fraction boils between 320 and 600 F, and the high-boiling fraction, between 600 and 670 F, the boiling point spread of the first fraction is 280 degrees, and that of the other fraction, 70 degrees; the boiling point range, or spread, of the first fraction is thus four times that of the high-boiling point fraction.

In another aspect of the invention, a mixture of l-olefins having 10 to 20 carbon atoms, obtained for example from the cracking of paraffin wax, is distilled into a lower boiling fraction boiling in about the range 330 F. to 585-620 F., and a higher boiling fraction boiling in about the range 585 620 F. to 670 F. Aromatic hydrocarbon is separately alkylated with each fraction under conventional alkylation conditions to produce two alkyl ates, which are then treated to isolate the heart-cut. When benzene is used as the aromatic hydrocarbon, the lowboiling alkylbenzene fraction boils in about the range 500 F. to 705750 F., and the higher boiling fraction in about the range 675725 F. to 780-800 F. The alkylbenzenes are then combined, and when the resulting mixture is sulfonated and neutralized, a superior product is obtained.

The following examples, in which parts are by weight, are given to illustrate the practice of the invention. Unsulfonated oil content was determined in conventional manner by extraction with petroleum ether of a solution of detergent in a mixture of water and ethanol.

Example 1 An essentially pure l-olefin mixture having a boiling range of 330-670 F. was obtained by distillation from thermally cracked petroleum-wax olefins... This olefin mixture (average molecular weight of 213),. 213 parts along with benzene, 780 parts was charged over a period of 1 hour to 200 parts of anhydrous liquid HF. During this time the mixture was well stirred and maintained at 32 F. After allof the olefin-benzene blend was charged, mixing was continued for an adidtional one-half hour. At the end of this time, stirring was stopped and the mixture separated into two layers. The HF layer was discarded, the hydrocarbon layer Was drained into a closed vessel containing ice and water, while at the same time 2000 parts of 20% KOH was added to the same vessel with continuous stirring. The organic layer was phase separated, washed with 2000 parts of water, and charged to a simple distillation column. Benzene and light alkylate boiling below 500 F. were taken as a forerun, the heartcut was that material boiling between 500 F. and 790 F., and amounted to 276 parts (93% weight).

The heart-cut alkylate, 205 parts, was charged to a sulfonation vessel and cooled to and maintained at 40-45 P. Then, while stirring, 209 parts of 22% oleum was added over a period of one-half hour. When all oleum was.

charged, the temperature was raised to 120 F. and stirring continued for 1 hour at this temperature. At the end of this time, 39 parts of Water was added over a period of 5 minutes while maintaining the temperature below 140 F. After all the water was added, the temperature was raised to and maintained at 150 F. Stirring was stopped; and after settling (about 1 hour), the lower acid layer was removed and discarded; the upper layer was drained into a dropping funnel. The upper layer was then added slowly to a well-stirred mixture of 225 parts of 12.5% aqueous sodium hydroxide maintained at a temperature below 110 F. Addition is continued until the slurry reaches a pH of 7.0-7.5 (Grammercy Universal Indicator). Analysis of the slurry by the methylene blue titration method showed it to contain 40% surface active material.

Of the slurry prepared above, 20 parts was placed in a beaker with 90 parts of 95% ethanol; and the two were stirred at 130-140 F. for about minutes. After cooling to 100 F., the solution was filtered. The beaker, salt cake, and funnel were washed once with parts of petroleum ether (boiling point 86l40 F.) and three times with 8 part portions of 95% ethanol. The filtrate and washes were placed in a separatory funnel and about 48 parts of water added to give a solution of 70 volume percent ethanol. The alcoholic solution (pH 7) was extracted with three -part portions of petroleum ether. The petroleum ether extracts were combined, washed with 70% ethanol, and then water. The petroleum ether was then filtered through two folded filter papers into a tared flask and evaporated on a steam bath to leave the unsulfonated oil, 0.18 part (2.2% of the surface active sulfonate).

Example 2 The same source of 1-olefiins as for Example 1 was distilled to give two fractionsone boiling from 330 F. to 600 F. and the second boiling from 600 F. to 670 F. The low-boiling fraction thus had a boiling point range 3.9 times that of the high-boiling fraction. Each fraction was separately alkylated as in Example 1. Each phenyl alkane was separately distilled to give as product two heart-cutsone boiling from 500 F. to 730 F. and the other boiling from 700 F. to 790 F.

The two heart-cuts were combined to give a total phenyl alkane mixture having a boiling point of 715 F. to 790 F. This material was sulfonated and analyzed for unsulfonated oil as in Example 1. From 20 parts of active material there was obtained only 0.08 part of unsulfonated oil (1.0%

Example 3 The procedure of Example 2 was repeated except that the first olefin fraction had a boiling range of 330 F. to 525 F. and the second olefin fraction had a boiling range of 525 F. to 670 F. (boiling range of low-boiling fraction 1.3 times that of the high-boiling fraction). After alkylation, the first heart-cut phenyl alkane had a boiling range of 500 F. to 650 F. and the second heart-cut phenyl alkane had a boiling range of 610 F. to 790 F. After combining and sulfonating, the unsulfonated oil content was found to be 0.16 part (2.0% based on surface active).

The examples all give the same detergent, i.e., a mixture of sodium C through C phenyl alkylbenzene sulfonates. However, by distilling the olefin feed into the two specified fractions (Example 2), a product having low unsulfonated oil (1.0%) is obtained. On the other hand, with no fractionation (Example 1) or distillation into two fractions outside the specified range (Example 3) leads to products of high unsulfonated oil (2.2% and 2.0%, respectively).

We claim:

1. In the process of preparing detergent alkylate by alkylating an aromatic hydrocarbon with a C -C l-olefin mixture to produce C -C alkylaryl hydrocarbons convertible by sulfonation and neutralization to a detergent active material, the improvement of producing an alkylaromatic hydrocarbon mixture which upon sulfonation and neutralization yields a detergent product characterized by a low unsulfonated oil content, which comprises separately alkylating said aromatic hydrocarbon with two contiguous fractions of said C -C l-olefin mixture, a lower-boiling fraction and a higher-boiling fraction, the boiling point spread of the lower-boiling fraction being about 3.0 to 5.8 times that of the higher-boiling fraction, to produce two alkylation products, isolating a detergent heart-cut fraction from each of the alkylation products and combining said heart-cuts before sulfonation and neutralization to produce a detergent active material having a low content of unsulfonated oil.

2. Process according to claim 1, wherein the C C l-olefin mixture is obtained by the cracking of paraffin waxes.

3. Process according to claim 2, wherein the aromatic hydrocarbon is a monophenyl compound.

4. Process according to claim 3, wherein the monophenyl aromatic hydrocarbon is benzene.

5. In the process of preparing detergent alkylate by alkylating benzene with C -C l-olefins to produce C C alkylbenzenes convertible by sulfonation and neutralization to a detergent active material, the improvement' of producing an alkylbenzene mixture which upon sulfonation and neutralization yields a detergent product characterized by a low unsulfonated oil content, which comprises before alkylation fractionating C -C l-olefins into a lower-boiling fraction boiling in about the range 330 F. to 585620 F. and a higher-boiling fraction boiling in about the range 585620 F. to 670 F., separately alkylating benzene with said fractions to produce lowerand higher-boiling alkylbenzene fractions, recovering a lower-boiling alkylbenzene fraction boiling in about the range 500 F. to 705 F.750 F. and a higher-boiling alkylbenzene fraction boiling in about the range 675 F.725 F. to 790800 F., and combining the alkylbenzene fractions before sulfonation and neutralization to produce the detergent active material.

6. Process according to claim 5, wherein the C -C l-olefins are obtained from the cracking of parafi'in waxes.

References Cited UNITED STATES PATENTS 2,655,530 10/1953 Nevison 260505 DELBERT E. GANTZ, Primary Examiner.

C. R. DAVIS, Assistant Examiner. 

1. IN THE PROCESS OF PREPARING DETERGENT ALKYLATE BY ALKYLATING AN AROMATIC HYDROCARBON WITH A C10-C20 1-OLEFIN MIXTURE TO PRODUCE C10-C20 ALKYLARYL HYDROCARBONS CONVERTIBLE BY SULFONATION AND NEUTRALIZATION TO A DETERGENT ACTIVE MATERIAL, THE IMPROVEMENT OF PRODUCING AN ALKYLAROMATIC HYDROCARBON MIXTURE WHICH UPON SULFONATION AND NEUTRALIZATION YIELDS A DETERGENT PRODUCT CHARACTERIZED BY A LOW UNSULFONATED OIL CONTENT, WHICH COMPRISES SEPARATELY ALKYLATING SAID AROMATIC HYDROCARBON WITH TWO CONTIGUOUS FRACTIONS OF SAID C10-C20 1-OLEFIN MIXTURE, A LOWER-BOILING FRACTION AND A HIGHER-BOILING FRACTION, THE BOILING POINT SPREAD OF THE LOWER-BOILING FRACTION BEING ABOUT 3.0 TO 5.8 TIMES THAT OF THE HIGHER-BOILING FRACTION, TO PRODUCE TWO ALKYLATION PRODUCTS, ISOLATING A DETERGENT HEART-CUT FRACTION FROM EACH OF THE ALKYLATION PRODUCTS AND COMBINING SAID HEART-CUTS BEFORE SULFONATION AND NEUTRALIZATION TO PRODUCE A DETERGENT ACTIVE MATERIAL HAVING A LOW CONTENT OF UNSULFONATED OIL. 